6 Answers
6

Easiest way I can think of to do it is if you bring up the file info (Apple + I) then add something into the Spotlight Comments field that you keep the same through the files you want, rinse and repeat for the files. Create a new Smart Folder, for the search option go to Other... and it'll bring up the full list, which will include Spotlight Comments.

For documents there is an app in the Mac App Store iDocuments Lite. It seems similar to iPhoto and/or iTunes but for documents.

Auto Import & Management

Organize and manage documents on your Mac using collections, folders and smart folders.

Quick tag, Open Metadata supported.

Search the documents by small clue like keywords, title, and author's name etc.

Auto Run, Batch process (full version)

Click to share (full version)

There are some other features available not listed above. The app puts everyone of your documents in an easy to access library. Haven't been able to find a single app that encompasses all file types rather a separate app for music, photo's, documents etc. The Lite version in the App Store is free, might be worth checking into. The Full version is $49.95.

There is no particularly complete way of replicating the libraries feature on Windows. The many options already offered make a great way to combine the existing files, but all fall down when it comes to adding new ones.

The problem is knowing where the default location for new files goes. In the Windows 7 system it's not just a collection of (say) 3 users picture libraries shown individually in a picture library, it's the contents of those libraries all lumped together without any distinction as to where the originally came from. A new file added into it would go into the users default library directory.

In our Smart Folder attempts to recreate this the folder would necessarily be read only, as it's not a genuine location, and the only way we can add files into the folder would be to go to the source and add them direct. Creating a collection of sym links, or using the Burn folder (Great tip for creating sym link folder collections by the way) has the benefits of allowing you to write into the folder direct, but you will still have a top level where each individual source is shown separately rather than an amalgamation of contents that you can also write into.

So, the short answer is a No, sadly, there no way to recreate this in the same way.

I found a hint about it, the idea is to make a saved search that scopes the first folder you want, edit the XXX.savedSearch in a text editor and add other folders to the scope, so that it looks like this

Make a Burn Folder (Finder > File > New Burn Folder) and drag those items you want to include into it. They will be aliases, but as far as I can tell (from a little research, without having used Windows 7) aliases are what Windows 7 is using for the contents of its Libraries. You can rename the Burn Folder and put it where you please and, of course, you could even burn it to a CD (but you don't have to).

Make an ordinary folder (Finder > File > New Folder) and fill it with aliases of those items you wish to place in it. This would be the roll-your-own method, I guess.

First, a disclaimer that I haven't worked with the Windows Library function, so if I've missed some major benefit or function, I apologize. As others have stated, Mac OS X doesn't currently directly support (what I would call) collections of files–groups of files related by user-defined criteria–directly. (Technically of course, a "folder" fits into this definition, but, ignoring aliases for the moment, a file can only live in one folder collection.)

A few years back Lifehacker posted Metadata as a 'filing system'. The idea is, in essence, to tag all of your files and use Spotlight and Smart Folders to find and "organize" those files.

On a smaller scale, I keep many of my text files in Yojimbo and use it to create collections. My writing workflow is now plaintext/markdown based, so Yojimbo is an archive of my writing. Once I drank the kool-aid, Yojimbo reduced my Documents folder, and it's hierarchy, significantly.

Yojimbo doesn't work for all file types though. EagleFiler brings many of Yojimbo's features to the Finder and can be applied to different file types. The caveat being that of these programs build a database of your files and you have to manage the files from within the software UI.

Enter Yep which uses OpenMeta tags, allowing you to move, copy and delete files freely using the Finder. Yep seemingly provides much of the functionality, flexibility and convenience of the Microsoft Library with the least imposition on workflow.

OpenMeta is an OS X Cocoa Objective - C technology that allows any
application to read and or write tags, ratings, etc to any file. It
works with 10.5 and 10.6

The idea of the project is for commercial, open source and in house
programs to be able to use OpenMeta for reading, writing and dealing
with user defined meta data. The metadata is stored in extended
attributes (xattr).

Some of the metadata stored can be stored in such a way so as to
trigger the Spotlight indexer to add the data to the Spotlight DB,
allowing it to be searchable.